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Biomedical subjects

Z J Twardowski

Publications and source records attributed to Z J Twardowski.

At least 19 recordsLinked to original sources
PubMed1996

Four-year experience with swan neck presternal peritoneal dialysis catheter.

The swan neck presternal catheter is composed of two flexible (silicon rubber) tubes joined by a titanium connector at the time of implantation. The exit site is located in the presternal or parasternal area. The catheter located on the chest was designed to reduce the incidence of exit site infections compared with peritoneal dialysis catheters with abdominal exit sites. From August 1991 to May 1995, 24 swan neck presternal catheters have been implanted in 24 patients for the following reasons: obesity nine patients, ostomies three patients, a suprapubic catheter one patient, previous problems with abdominal catheters two patients, desire to use a bathtub five patients, need to use a whirlpool one patient, need to wear sweatpants with an elastic waistband one patient, and body image two patients. In the same period, 47 abdominal swan neck catheters were implanted in 44 patients who preferred catheters with the exit on the abdomen. Presternal catheters tended to perform better regarding exit and tunnel infections, even though they were implanted in several patients in whom regular catheters with the exit on the abdomen would be difficult or impossible to implant. Two-year survival probability of presternal catheters was 0.88 +/- 0.14 (+/- SE). Recurrent/refractory peritonitis was the only reason of catheter failure. The differences in results between presternal and abdominal catheters were statistically insignificant; only the use of antibiotics to treat exit site infection was significantly higher with abdominal catheters. Patient acceptance of the exit position was good; at least seven patients preferred presternal catheter for psychological or body image reasons. We conclude that the swan neck presternal catheters provide excellent results comparable to those achieved with swan neck abdominal catheters. The catheter seems suitable for any patient commencing peritoneal dialysis and is particularly useful in extremely obese patients (body mass index > 40 kg/m2) and those with ostomies. The catheter exit location in the chest may be preferred by some patients, both men and women, for psychological or body image reasons. No specific contraindications to the presternal catheter implantation have been identified.

Abdomen↗
PubMed1995

Expected white blood cell counts and differentials in a rat model of peritoneal dialysis.

OBJECTIVE: The purpose of this study was to establish baseline dialysate white blood cell (WBC) counts and differentials in noninfected rats on peritoneal dialysis (PD). DESIGN: Sixteen male Sprague-Dawley rats underwent PD in the first protocol, and eight from the 16 continued PD in the second through fourth protocols. At the beginning of the experiments, all animals had a PD catheter implanted and were initiated on PD with 1.5% dextrose dialysis solution twice daily. In the first protocol, WBC counts and differentials were assessed from day 4 to day 15 of dialysis in noninfected animals to establish "normal values" for such a rat model. In protocol 2, WBC counts and solute concentrations in small aliquots of dialysate obtained from the catheter were compared to values in well-mixed total drainage. Protocol 3 was designed to assess effects of dwell time on WBC counts. Protocol 4 examined the effect of glucose concentration of dialysis solution on WBC counts. RESULTS: In the first protocol, the mean dialysate WBC counts were significantly higher on the fourth day of dialysis, but stabilized below 2500 cells/mm3 by the eighth day. The percentage of neutrophils was stable around 20%-25%. In the second protocol, we found aliquots < 1 mL might underestimate the dialysate WBC count compared to the complete drainage. In the third protocol, WBC counts increased as cycle time became longer, but the percentage of neutrophils remained below 50%. In the fourth protocol, we did not find any effects of glucose concentration of instilled solutions on WBC counts and differentials. CONCLUSION: This study of WBC counts and differentials in noninfected rats on peritoneal dialysis establishes the range above which infection should be suspected. WBC counts increase with cycle time. Small dialysate aliquots may underestimate WBC counts. Glucose concentration does not effect WBC counts.

Animals↗
PubMed1995

Predicted and measured daily creatinine production in CAPD: identifying noncompliance.

OBJECTIVE: To evaluate the ratio of measured creatinine (Cr) production to predicted creatinine production as an index of noncompliance in patients on continuous ambulatory peritoneal dialysis (CAPD). DESIGN: A cross-sectional analysis. PATIENTS: One hundred and twenty-one patients on CAPD. MEASUREMENTS: We have calculated Cr production from measured Cr outputs in 24-hour collections of urine and dialysate. Predicted Cr productions were calculated from standard tables. Weekly KT/V urea and weekly Cr clearances were determined from the same 24-hour urine and dialysate collections. Lean body mass (LBM) was calculated from the Cr production. Serum albumin concentration was measured. RESULTS: The ratio of measured/predicted Cr production correlated positively and significantly with weekly KT/V urea, the protein equivalent of nitrogen appearance (PNA), weekly Cr clearance, and LBM. There was a decline in serum albumin concentration at ratios greater than 1.24, supporting the opinions of previous authors who have suggested that ratios greater than 1.24 are highly suggestive of noncompliance with the dialysis prescription. Defining noncompliance as a ratio greater than 1.24 implied that at least 5% of the female and 17% of the male patients were noncompliant. CONCLUSIONS: Declining serum albumin concentrations at higher ratios of measured/predicted Cr production support the opinion that this is an index of noncompliance. However, not all noncompliant patients necessarily have a ratio greater than 1.24. Weekly KT/V urea, weekly Ccr and LBM are all artifactually increased by "washout effects" if all exchanges are done only or mainly on the collection day.

Body Mass Index↗
PubMed1995

Continuous ambulatory peritoneal dialysis and the heart.

OBJECTIVE: To review clinical research pertaining to continuous ambulatory peritoneal dialysis (CAPD) and the heart. DATA SOURCES: A Medline computer search was employed to identify appropriate references from 1970 - 1994. Indexing terms were: continuous ambulatory peritoneal dialysis, hemodialysis, heart or cardiac, left ventricle, coronary artery disease, and survival. English and non-English language abstracts were scrutinized. STUDY SELECTION: Forty-six studies were reviewed and utilized. Numerical data extracted are reported in this review as they were reported in the original article. RESULTS: This review provides a broad-based survey of studies pertaining to CAPD and the heart. Most of the studies relate to CAPD and left ventricular structure or function. Little information exists concerning CAPD and coronary artery disease, valvular disease, pericardial disease, and cardiac arrhythmias. Studies pertaining to patient survival on CAPD identify coronary artery disease and congestive heart failure as major risk factors, but in-depth quantification of these cardiovascular disorders is lacking in the literature. CONCLUSIONS: CAPD is capable of decreasing left ventricular (LV) volume and improving LV systolic function in patients with LV enlargement and those with LV systolic dysfunction. The effect of CAPD on left ventricular hypertrophy (LVH) and LV diastolic function is variable. CAPD produces symptomatic improvement in patients with refractory congestive heart failure, but its effect on survival in such patients is uncertain. Atherogenic lipid abnormalities occur in CAPD patients. The clinical significance of these abnormalities is uncertain. Coronary artery bypass surgery can be performed safely and effectively on CAPD patients. CAPD is not arrhythmogenic. Survival of CAPD patients is similar to that of hemodialysis patients except in elderly diabetics for whom it is slightly lower.

Arrhythmias, Cardiac↗
PubMed1995

Preliminary evaluation of silver-coated peritoneal catheters in rats.

Silver is known to have powerful antibacterial properties against a variety of micro-organisms and has a low toxicity and a favorable biocompatibility profile. This study was designed to evaluate the effectiveness of silver-coated catheters in preventing early exit-site infection and to assess tunnel morphology. Seven male Sprague-Dawley rats underwent simultaneous implantation of two double-cuffed, silver-coated silicone rubber and standard silicone rubber catheters. Weekly observations and photographs documented exit-site characteristics. The animals were sacrificed and catheters removed and processed for histopathology of the external tunnel at 5 weeks. Exit sites of silver-coated catheters tended to have less inflammation and infection and healed better than those of uncoated catheters; however, these data did not achieve significance using the Wilcoxon signed-rank test. Sections of the external tunnel of well-healing exit sites showed an epithelialized tract with granulation tissue near the cuff and significant invasion of the external cuff by collagen with a mild neutrophilic inflammatory response. In contrast, the histology of the external tunnel of infected exists revealed exudate overlying inflammatory granulation tissue and a variable degree of fibrosis of the cuff. When the exit sites appeared similar, no significant histopathological differences in sinus tract and cuff morphology were noted with either silver or standard catheters. In conclusion, these findings suggest that silver coating of catheters may decrease the incidence of early exit-site infections and allow better ingrowth of the catheter.

Animals↗
PubMed1995

Rat model of peritoneal fibrosis: preliminary observations.

The aim of this study was to establish a rat model of peritoneal fibrosis. After insertion of peritoneal catheters into 18 rats, the rats were divided into three groups. All animals were dialyzed twice a day with 4.25% Dianeal containing heparin. Group 1 rats (control) received antibiotics (vancomycin and gentamicin) in each exchange: group 2 rats were inoculated with Escherichia coli (5 x 10(6) in 5 mL of saline) at the beginning of the study; group 3 rats were treated with antibiotics after Escherichia coli inoculation; they also received a second inoculation of Escherichia coli after the second week of the study. By the end of the second week, group 2 rats were sacrificed because of catheter problems. Group 1 and 3 rats were sacrificed after 4 weeks of dialysis. A weekly peritoneal equilibration test (PET) was performed in each rat. The comparison of the PET results from the beginning and end of the study showed an increased permeability to glucose (p < 0.05) and total protein (p < 0.05) in group 3, which was not noted in group 1. In histology samples there was only delicate fibrosis with cellular infiltration in the peritoneum in group 1 rats. These changes were much more prominent in group 3 rats. This study suggests that E. coli peritonitis causes peritoneal fibrosis in rats, but to have a sclerosing encapsulating peritonitis (SEP) model this experiment must be carried out for a longer time.

Animals↗
PubMed1995

Spontaneous peritonitis and peritoneal fibrosis in rats on peritoneal dialysis for 9 weeks.

To investigate characteristics of peritonitis in rats on peritoneal dialysis (PD), we retrospectively studied 36 cases of peritonitis in 23 rats. After breakin dialysis postcatheter insertion, the animals were dialyzed twice daily with 1.5% or 4.25% Dianeal for 8 weeks. White blood cell (WBC) count with differentials and microbiological culture of the dialysate were examined twice weekly. Peritonitis was treated with cefazolin and tobramycin until the tenth day after the dialysate became clear. The peritoneal equilibration test (PET) was performed at weeks 2, 6, and 10. The dialysate was obtained at 0, 2, and 4 hours for glucose assay. The peritoneal cavity was inspected, and peritoneal tissue specimens were taken. There were 10 single episodes of peritonitis, 7 recurrences, and 6 reinfections. The organisms isolated were Staphylococcus aureus in 24 cases of peritonitis and Escherichia coli in 6 cases of peritonitis. The average treatment period was 16 days. The glucose absorption ratio became higher over time in single episodes of peritonitis, but was unchanged in recurrences and reinfections. Sixteen adhesions, 1 abscess, and 12 sclerotic retractions of the mesentery were observed. Fibrotic thickening of the peritoneum was found histologically in all animals. In spontaneous peritonitis in rats, we often found complicated clinical courses, catheter closure, intraperitoneal adhesion, and fibrotic thickening of the peritoneum.

Animals↗
PubMed1995

Absorption of iron dextran from the peritoneal cavity of rats.

We investigated the absorption rate and acute toxicities of intraperitoneal iron dextran in rats. Eighteen Sprague-Dawley rats were divided into three groups (n = 6). The animals were given standard 1.5% Dianeal (group 1) or 1.5% Dianeal containing iron in a concentration of 2 mg/L (group 2) or 10 mg/L (group 3) as iron dextran. First, a predialysis blood sample was obtained, and 25 mL of the designated dialysis solution was instilled into the peritoneal cavity. After a 6-hour cycle the dialysate was drained, and a postdialysis blood sample and specimen of the peritoneum were obtained. The iron concentrations of the dialysis solution, the dialysate, and both serum samples were determined. Histological samples were processed by hematoxylin and eosin and Prussian blue stain. Results of the iron concentration (mg/L) of the dialysis solution, the dialysate, and the percent of the absorbed iron were as follows: group 1: 0.00, 0.20 +/- 0.15, N/A; group 2: 2.24, 0.66 +/- 2.8, 73.8 +/- 11.0; group 3: 9.84, 2.12 +/- 0.62, 80.8 +/- 5.7. The serum iron concentration did not change. No abnormal findings were found histologically. More than 70% of the iron dextran was absorbed from the peritoneal cavity of the rats during a 6-hour peritoneal dialysis exchange. Intraperitoneal iron dextran may be an alternative route of iron delivery.

Absorption↗
PubMed1994

Hyperbaric oxygen therapy in calciphylaxis-induced skin necrosis in a peritoneal dialysis patient.

A 58-year-old white woman on continuous ambulatory peritoneal dialysis for 2 years developed calciphylaxis-induced necrotic skin lesions over both lower extremities. Despite subtotal parathyroidectomy and other conventional measures, skin lesions continued to worsen. Mapping of transcutaneous oxygen pressure showed markedly low values in involved areas. Skin ulcers completely healed after 38 sessions of hyperbaric oxygen therapy. The results in our case indicate that hyperbaric oxygen therapy may be useful in the treatment of skin ulcers secondary to calciphylaxis.

Calciphylaxis↗
PubMed1994

Changes in the peritoneal equilibration test in selected chronic peritoneal dialysis patients.

Fifty-five patients on chronic peritoneal dialysis with two or more peritoneal equilibration tests (PET) performed between 1983 and 1992 with a mean interval of 21.9 +/- 22.7 months were studied retrospectively. Repeated PET were performed when transport changes were suspected rather than routinely. According to the initial PET, there were 16 high (HI), 17 high-average (HA), 15 low-average (LA), and 7 low (LO) transporters. There was a significant decrease in the mean creatinine dialysate to plasma ratio (D/P creatinine) in the HI transporters and an increase in the LA and LO transporters. The mean dialysate to instilled glucose ratio (D/Do) significantly increased in the HI transporters. The change in both the D/P creatinine and the D/Do of an individual strongly and inversely correlated to their respective initial values. The change in D/P creatinine and D/Do were significantly and inversely correlated to each other, indicating an actual transport change. No correlation was found between the change in transport with peritonitis episodes or frequencies. The centripetal [corrected] change of transport toward average described here may explain why low clearances or low ultrafiltration rates due to rapid transport are infrequent causes of peritoneal dialysis technique failure, and why patients who have been dialyzed for a long period are usually HA transporters.

Biological Transport, Active↗
PubMed1994

Lean body mass estimation by creatinine kinetics.

A new technique for estimating lean body mass (LBM) from creatinine kinetics has been developed. It is based on the principle that creatinine production is proportional to LBM and that, in the steady state, creatinine production is equal to the sum of creatinine excretion (urinary and dialytic) and metabolic degradation. This technique was applied to 17 normal subjects, 26 stable, chronic hemodialysis (HD) patients, and 71 stable, chronic peritoneal dialysis (PD) patients. In the HD group, LBM was also determined by bioimpedance in 11 patients and calculated from total body water, measured as the volume of urea distribution of a sterile urea infusion, in 15 patients. In normal subjects and in the PD group, LBM was assessed by creatinine kinetics as well as by bioimpedance, near infrared, and anthropometric techniques. In the HD patients, LBM by creatinine kinetics correlated significantly with LBM from total body water and the bioimpedance technique. There was no statistical difference between the total body water and creatinine kinetics techniques, but the bioimpedance values were systematically higher than those obtained by the kinetic technique. In the PD group and in normal volunteers, LBM values by creatinine kinetics correlated significantly with the other methods but were lower. Forty-seven percent of the HD patients and 66% of the PD patients had significantly lower LBM by creatinine kinetics than expected for their sex and age. Estimation of LBM by creatinine kinetics is proposed as a simple and convenient technique for the routine nutritional assessment of dialysis patients.

Anthropometry↗
PubMed1994

Weight limitations for weekly urea clearances using various exchange volumes in continuous ambulatory peritoneal dialysis.

OBJECTIVE: To calculate the relationships of weekly KT/V urea to standard body weight with different exchange volumes (2, 2.5, or 3 L) for continuous ambulatory peritoneal dialysis (CAPD) in functionally anephric patients and to display the results in graphic form. DESIGN: Theoretical calculations using previously measured 24-hour dialysate/plasma urea values in 77 CAPD patients and other defined components of weekly KT/V urea. SETTING: Measurements and calculations in theoretical patients doing standard CAPD with four daily exchanges. PATIENTS: Theoretical functionally anephric patients on standard CAPD as above. INTERVENTIONS: Theoretical calculations based on instillation of 2-, 2.5-, and 3-L exchange volumes. MAIN OUTCOME MEASURES: Weekly urea clearances normalized to total body water (weekly KT/V urea). The values using different exchange volumes were related to standard body weight. RESULTS: Although a minimum recommended weekly KT/V urea target is arbitrary, the results illustrate the range of flexibility of CAPD relative to KT/V urea values with variations in exchange volume. The standard weights above which anephric patients on CAPD using four exchanges per day with 2-, 2.5-, and 3-L exchanges cannot reach a weekly KT/V urea target of 1.7, have been identified. The range of weekly KT/V urea levels possible with different exchange-volume programs has been graphically illustrated. CONCLUSIONS: Weights above which a weekly KT/V urea of 1.7 cannot be reached in functionally anephric patients are 64, 77.6, and 91 kg for CAPD using 2-, 2.5-, and 3-L exchanges, respectively.

Body Weight↗
PubMed1994

Computer interaction: catheters.

A computer interaction session conducted during the 14th Annual Peritoneal Dialysis Conference in Orlando, Florida, on January 24, 1994, revealed the preferences and practices of 650-690 respondents voting on questions related to peritoneal catheters. Compared to the surveys conducted in 1987 and 1989, the most striking change was an increase in the use of catheters with the bent intramural segment, particularly the Swan neck catheter, and an increase in the use of catheters with the coiled intraperitoneal segment. The Tenckhoff catheter continued to be the most popular, although its use was decreasing. The remaining catheters were used in small numbers. The vast majority of nephrologists remain convinced of the superiority of double cuff catheters over single cuff ones, and the use of the former continued to exceed 70%. Essentially no change occurred in the method of catheter placement; surgical dissection (72.7%) remained the most popular implantation method. Surgeons were primarily responsible for catheter implantations (87.4% of votes). The use of prophylactic antibiotics prior to catheter implantation seems to be increasing. The majority of respondents did not consider a Staphylococcus aureus nasal carrier status as important in the development of catheter-related infections, as indicated by the small number of centers where routine culture of nares was performed. The majority of institutions delayed ambulatory peritoneal dialysis after catheter implantation, but ambulatory peritoneal dialysis was started in some centers (5.7% of votes) in the immediate postimplantation period.

Attitude of Health Personnel↗